Tool connecting device for robot hand

ABSTRACT

A robot hand tool linkage device includes a locking mechanism and an actuation shaft driven between a lock position and a release position. A piston moves an actuation shaft upward and downward to cam outward a plurality push rods urging outward a plurality arc-shaped locking members. The locking members are captured under an arcuate surface of a tool plate which is thereby attached. A resilient member engages an outer groove in each of the locking members to urge them inward. When the outward force on the locking members is released, the resilient member moves the locking members inward to reduce their combined diameter sufficiently to disengage from the arcuate surface, and thereby to release the tool plate.

BACKGROUND OF THE INVENTION

1. Background of the Invention

The present invention relates to a tool linkage device for a robot hand.In particular, the present invention relates to a robot hand toollinkage device in which a plurality of radially provided rod members actas joining members for a locking mechanism which reliably connects amaster plate and a tool plate.

2. Description of the Related Art

A robot hand tool linkage device selectively attaches and detachesseveral types of tools from a hand output part of a robot hand.Generally, robot hand tool linkage devices have an inner assembly(master plate) that is attached to a hand output part of a robot hand,an outer assembly (tool plate) onto which a tool is attached, and alocking mechanism which locks the inner assembly and outer assembly.

U. S. Pat. No. 4,696,524 discloses a robot hand tool linkage device thatcan rapidly connect and disconnect an inner assembly and an outerassembly. The locking mechanism for this robot hand tool linkage devicehas a piston member, a plurality of ball members acting as the joiningmembers, and a ball receiver as a latching part.

The piston member is supported by the inner assembly and is slidablefrom a lock position to a lock release position. The ball member ishoused and retained in a housing hole of an approximately cylindricalball retainer which surrounds the outer perimeter of the output part ofthe piston member connected to the inner assembly.

The ball member can move in a direction which is perpendicular to thesliding direction of the piston member (henceforth referred to as theperpendicular direction). Consequently, with the housing hole of theball retainer, its inner diameter side and outer diameter side arelinked in the perpendicular direction, and the ball member moves in theperpendicular direction inside the housing hole.

The ball receiver is provided on the outer assembly. The ball receivercontacts the ball member on its tapered surface. During operation, whenthe piston member moves to the lock position, the ball receivercooperates with the ball members to connect the inner assembly and theouter assembly.

For the ball retainer, a plurality of flat springs are provided alongthe outer perimeter surface of the ball retainer excluding the housingholes. Particularly when the inner assembly and outer assembly are beingdisconnected, the ends of adjacent flat springs assist in preventing theloss of ball members and urge the ball members toward the inner diameterof the ball retainer.

Japanese Laid-Open Patent Number 4-63688 provides a robot hand toollinkage device wherein a plurality of flat springs are on the outerperimeter surface of the ball retainer. The loss of ball members fromthe ball retainer is prevented by these flat springs.

Unfortunately, according to the robot hand tool linkage device describedabove, a plurality of flat springs are required to prevent the loss ofball members by impelling the ball members toward the inner diameter ofthe ball retainer. As a further detriment, the above designs require alarge number of parts, and the structure is detrimentally complex,leading to higher manufacturing costs.

Since ball members are used as joining members, there is point contactor line contact between the spherical surface of the ball member and theflat surface of the ball receiver. The actual contact surface area isdetrimentally small resulting in adversely high contact surfacepressure.

Additionally, since the structure has a plurality of ball members placedalong the entire perimeter, the contact parts between the ball memberand the ball receiver is present only intermittently along the entireperimeter, and the contact surface pressure of the locking mechanism, asa whole, is detrimentally high. This high contact surface pressureresults in substantially shortened mechanical life and reducesreliability.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a tool linkagedevice for a robot hand which overcomes the drawbacks of the related artdescribed above.

It is another object of the present invention to provide a robot handtool linkage device that reliably prevents the loss of the joiningmember, reduces the number of parts, simplifies the structure anddesign, reduces contact pressure between operable parts, maintains lowmanufacturing costs, and increases the durability of the device whileretaining operational effectiveness.

The present invention relates to a robot hand tool linkage device thatis equipped with a master plate that is connected to the output part ofa robot hand, a tool plate onto which a tool is connected, and a lockingmechanism that releasably locks the master plate and tool plate.

In particular, with the robot hand tool linkage device of the presentinvention, the locking mechanism comprises: an actuation shaft that issupported by the master plate and is driven between a lock position anda release position by an air cylinder inside the master plate; aring-shaped retainer that is affixed to the master plate and thatsurrounds an outer perimeter of an output part of the actuation shaft; aplurality of rod insertion holes that are formed in an inner perimeterwall of the retainer and are formed penetrating in a radial directionthat is perpendicular to a sliding direction of the actuation shaft; aring-shaped groove that is formed on the retainer on an outer perimeterside of the plurality of rod insertion holes and that is formed with theouter perimeter side open; a plurality of push rods that are attachedmovably in the plurality of rod insertion holes and that transfer theoutput of the actuation shaft radially outward; and a plurality ofarc-shaped locking members that are attached in a manner allowing forsliding in a radial direction in the ring-shaped groove and that are incontact with or are coupled with the ends of the push rods.

With this robot hand tool linkage device, when connecting the tool plateand the master plate, after positioning the master plate and the toolplate and forming a temporary connection, an actuator shaft is moved toa lock position by an air cylinder. Thereupon, each push rod is pushedradially outward, and a plurality of arc-shaped locking members slidesradially outward where it and joins with the tool plate. With this, thetool plate and the master plate are securely locked. When releasing theconnection between the tool plate and the master plate, the actuatorshaft is moved to a lock release position by the air cylinder.Thereupon, the plurality of arc-shaped locking members moves to asmaller radius, and each push rod moves radially inward. Afterwards,when the pin connections and the like between the tool plate and themaster plate are released, the connection between the tool plate and themaster plate is completely released.

Other preferred constructions for the present invention are described inthe preferred embodiments of the present invention.

The above, and other objects, features and advantages of the presentinvention will become apparent from the following description read inconjunction with the accompanying drawings, in which like referencenumerals designate the same elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-section of a tool linkage device of thepresent invention.

FIG. 2 is a partial cross-section of a tool linkage device in anactuation state of the locking mechanism.

FIG. 3 is a partial longitudinal cross-section of a different phase ofthe tool linkage device.

FIG. 4 is a longitudinal section of a different phase of the toollinkage device.

FIG. 5 is a horizontal section with an actuator shaft in a releaseposition.

FIG. 6 is a horizontal section with the actuator shaft in a lockposition.

FIG. 7 is a plan view of a push rod.

FIG. 8 is a front view of a push rod.

FIG. 9 is a partial expanded plan view of an arc-shaped locking member.

FIG. 10 is a cross-section along line X—X of FIG. 9.

FIG. 11 is a cross-section along line XI—XI of FIG. 9.

FIG. 12 is a longitudinal section of a tool linkage device in analternative embodiment of the present invention.

FIG. 13 is a longitudinal section of FIG. 12 in an actuation state ofthe locking mechanism.

FIG. 14 is a horizontal section of the actuator shaft in a releaseposition.

FIG. 15 is a horizontal section with the actuator shaft in a lockposition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-4, a tool linkage device 1 for a robot handincludes a master plate 2 that connects to an output part H of a robothand (not shown), a tool plate 3, a locking mechanism which releasablylocks together master plate 2 and tool plate 3and an air cylinder 7.During operation, one tool (not shown) from the multitude of possibletools (not shown) is connected to tool plate 3.

Master plate 2 includes a master plate body 5 and a lid part 6. Masterplate body 5 is approximately cylindrical. A lid part 6 is affixed to anupper end of master plate body 5.

A cylinder hole 8 of air cylinder 7 is formed in an upper half of masterplate body 5. A retainer joining hole 9, which is larger in diameterthan cylinder hole 8, is formed on a lower half of master plate body 5.A connector 10, for securing electric wires (not shown) that powersensors and switches (not shown) on the tool(not shown) is provided at aside of master body plate 5.

Air cylinder 7 is located in master plate 2. A piston member 13, of aircylinder 7, is fitted in a sealed and slidable manner in cylinder hole8. Sets of seal members 11 and 12 retain pressure in air cylinder 7,during operation. Seal member 13 a slidably seals seal member 13 tocylinder hole 8.

An actuator shaft 14 is affixed to a lower end of piston member 13.Actuator shaft 14 extends-downwards and away from piston member 13.During operation, actuator shaft 14 is raised and lowered by aircylinder 7 from a lock position (shown in FIG. 1) to a release position(shown in FIG. 2), as will be described.

A first actuation chamber 8 a, is formed in cylinder hole 8 in the lockposition, between piston member 13 and lid part 6.

A connection fitting 16A, threadably joins master plate body 5, forsupplying and releasing pressurized air to first actuation chamber 8 avia a passage hole 15.

A second actuation chamber 8 b consists of a lower part of cylinder hole8 and an annular depression 17 a in retainer 17. A connection fitting16B, threadably joined to master plate body 5, supplies and releasespressurized air from actuation chamber 8 b through a passage hole 15. Inoperation, pressurized air from a pressurized air supply source (notshown) is supplied to and released from air cylinder 7 by respective airhoses (not shown), connection fittings 16A, 16B, and passage holes 15.

Tool plate 3 consists of an approximately cylindrical tool plate body 3a and a ring-shaped joining ring 21, together with other elements.Ring-shaped joining ring 21 is placed inside a step part formed in theinner perimeter of the upper half of tool plate body 3 a. Joining ring21 is affixed to tool plate body 3 a by a plurality of bolts 22. Theinner surface of joining ring 21 includes a tapered joining surface 21 ain which the inner diameter becomes smaller toward the top and acylindrical surface 21 b which extends downward from the lower end oftapered joining surface 21 a. A plurality of tapered pin holes 21 ccapable of joining with a plurality of tapered pins 28 (refer to FIG. 3)are formed on joining ring 21. A connector 23 for the electric wiresthat power the sensors and switches of the tool and which connects withconnector 10 is affixed to tool plate body 3 a.

In order to supply pressurized fluid of two systems, for example, ofpressurized air and hydraulic pressure and the like to the tool sidefrom the robot side, as shown in FIGS. 1-4, for example, four connectionfittings 24A-24D are provided near the outer surface of master platebody 5. Four connection fittings 25A-25D (only 25B, 25C are shown)corresponding to four connection fittings 24A-24D are provided near theouter surface of tool plate body 3 a. When master plate 2 and tool plate3 are connected, the upper and lower fluid passages are connected via apassage 26.

Referring to FIGS. 1, 2, and 5-11, locking mechanism 4 has an actuatorshaft 14 that is raised and lowered by air cylinder 7, a ring-shapedretainer 17, four rod insertion holes 18, a ring-shaped groove 31, fourpush rods 19, and four arc-shaped locking members 20.

The upper half of retainer 17 fits inside retainer joining hole 9 ofmaster plate body 5. Retainer 17 is secured to master plate body 5 by aplurality of bolts. Retainer 17 includes a plurality of tapered pins 28that can fit into a plurality of pin holes 21 c of joining ring 21. Onthe inner perimeter side of the upper half of retainer 17, a guidecylinder 29 that is formed in the shape of a cylinder surrounds theoutside of the output part of actuation shaft 14. A seal member 30 isalso provided on guide cylinder part 29.

A ring-shaped groove 31 on the lower half of retainer 17 is open on theouter perimeter side. A ring-shaped wall 17 b is formed belowring-shaped groove 31, and an inner perimeter wall 17 c is formed to theinside of ring-shaped groove 31. Inner perimeter wall 17 c is a unitarycontinuation of guide cylinder 29. Four rod insertion holes 18 areformed on inner perimeter wall 17 c, passing in a radial direction thatis perpendicular to the sliding direction of actuator shaft 14. Rodinsertion holes 18 are formed at 90 degree intervals along thecircumference. The outer perimeter end of ring-shaped wall 17 b isslightly smaller in diameter than the inner perimeter surface of joiningring 21.

A push rod 19 is carried in each rod insertion hole 18 free to move inthe radial direction described above. In addition, push rod 19 isconstructed so that the output of actuator shaft 14 is transmittedradially outward.

Referring to FIGS. 5-8, an inner end 19 a of each push rod 19, whichreceives the output of actuator shaft 14, is a partial sphere. On theouter perimeter part of push rod 19, four grease grooves 19 b are formedin the radial direction at 90 degree intervals around the circumference.

Referring to FIGS. 1,2, 6 and 9-11, four arc-shaped locking members 20are attached to ring-shaped groove 31 in a manner that allows forsliding in the radial direction. A depression 20 e is formed near thecenter of the arc in the inner perimeter part of each arc-shaped lockingmember 20. The outer end of each push rod 19 loosely fits into adepression 20 e. The outer end of each push rod contacts depression 20e. An arc groove 20 a is formed on the outer perimeters of each of thefour arc-shaped locking members 20. A C-ring shaped spring member 32 isfitted into arc grooves 20 a. The four arc-shaped locking members areelastically urged toward a smaller radius by spring member 32. Afastening hole 20 b on one of the four arc-shaped locking members 20fastening spring member 32 to its outer perimeter.

An arc-shaped joining surface 20 c is formed near the outer perimeter ofeach arc-shaped locking member 20. Arc-shaped joining surface 20 c canjoin with tapered joining surface 21 a of joining ring 21 and has asmaller radius toward the top. When actuation shaft 14 is at the lockposition shown in FIG. 2, arc-shaped joining surfaces 20 c of the fourarc-shaped locking members 20 are in surface contact with and joins withtapered joining surface 21 a. When actuation shaft 14 is in the releaseposition shown in FIG. 1, arc-shaped joining surface 20 c has a smallerradius than tapered joining surface 21 a, thus permitting arc-shapedjoining surface 20 c to separate from tapered joining surface 21 a. Aplurality of grease grooves 20 d are formed on the upper and lowersurfaces of each arc-shaped locking member 20. Grease grooves 20 d areformed at an equal spacing, and they extend a set length in the radialdirection from the inner edge to the outer edge.

Although not shown in the figures, master plate 2 is coupled in advancewith output part H of a robot hand. The desired tool is coupled inadvance with tool plate 3. Linkage tool plate 3 and master plate 2,using the robot hand, are brought closer together. Their shaft centersand phases are aligned aided by engagement between the plurality oftaper pins 28 on master plate 2 and the plurality of tapered pin holes21 c on tool plate 3. Thus, master plate 2 and tool plate 3 arepositioned to form a temporary linkage.

Next, referring to FIGS. 2 and 6, while releasing the air insideactuation chamber 8 b, pressurized air is introduced inside actuationchamber 8 a. This lowers and piston member 13 and actuation shaft 14 tothe lock position. Thereupon, each push rod 19 is pushed outward in theradial direction by actuation shaft 14, and the four arc-shaped lockingmembers 20 slide radially outward. Each of the arc-shaped joiningsurfaces 20 c joins with the tapered joining surface 21 a of joiningring 21. As a result, tool plate 3 is securely locked to master plate 2.

Referring to FIGS. 1 and 5, for releasing the linkage between tool plate3 and master plate 2, pressurized air is introduced into actuationchamber 8 b while the air inside actuation chamber 8 a is released.Piston member 13 and actuation shaft 14 are raised to the lock releaseposition. Thereupon, by the urging force of spring member 32, the fourarc-shaped locking members 20 move inward toward a smaller radius.Arc-shaped joining surfaces 20 c of arc-shaped locking members 20separate from the tapered joining surface 21 a of joining ring 21, andthe linkage between tool plate 3 and master plate 2 is released.

In the prior art, a plurality of ball members as the joining member isplaced over the entire perimeter. As a result of this construction, thecontact portion between the ball member and the ball receiver is presentonly intermittently over the entire perimeter, and the contact surfacepressure of the locking mechanism as a whole becomes high. However, withtool linkage device 1, because a plurality of arc-shaped locking members20 are used as the joining member, the contact portion betweenarc-shaped locking members 20 and tapered joining surface 21 a ispresent almost continuously over the entire perimeter. As a result, thecontact surface pressure of locking mechanism 4 as a whole is reduced.Therefore, the life span of locking mechanism 4 is lengthened, and thedurability of the device is improved.

The plurality of push rods 19 are movably attached to the plurality ofrod insertion holes 18. The plurality of arc-shaped locking members 20abutting ring-shaped groove 31 are elastically urged to a smaller radiusby C-ring shaped spring member 32. As a result, loss of push rods 19 orarc shaped locking members 20 from retainer 17 is reliably prevented.Therefore, the plurality of flat springs and the like used forpreventing loss of the joining member in the prior art becomesunnecessary, the number of parts is reduced, and the construction issimplified.

Arc-shaped joining surface 20 c formed on arc-shaped locking member 20is capable of surface contact with tapered joining surface 21 a ofjoining ring 21. As a result, because its contact surface area isgreatly increased compared with the contact surface area of the ballmembers in the prior art, the contact surface pressure required forsecure attachment is reduced, and the durability of locking mechanism 4is greatly improved. Therefore, the durability of robot hand toollinkage device 1 is greatly improved.

Next, a modification mode in which the present embodiment is partiallymodified is described. However, elements that are essentially the sameas with the main embodiment described above are given the same numerals,and their descriptions are omitted.

1) The outer end of push rods 19 can be joined tightly with depression20 e of arc-shaped locking member 20, they can be coupled by welding, orthey can be coupled using adhesives or screws, and the like. Whenlinkage push rod 19 with arc-shaped locking member 20, depression 20 eis not always necessary and may be omitted.

2) Referring to FIGS. 12-15, with tool linkage device 1A, a surfacecontact part 35 is formed on the portion of push rod 19A that contactsthe output part of actuation shaft 14. Surface contact part 35 makessurface contact with one portion of the surface of actuation shaft 14. Apair of flat parts 36 is formed on the outer end portion of the outerperimeter surface of each push rod 19. Using flat parts 36, the outerend part of push rod 19A is fitted inside and screws together witharc-shaped locking member 20.

In other words, surface contact part 35 of push rod 19A is in stablesurface contact with one part of the surface of actuation shaft 14.Otherwise, tool linkage device 1A is constructed the same as theembodiment described above. According to tool linkage device 1A, becausepush rod 19A and actuation shaft 14 are in surface contact, the contactsurface area is even larger than the embodiment described above, and therequired surface contact pressure is further reduced. The durability oftool linkage device 1A is further improved.

3) Each push rod and arc-shaped locking member can be formed unitarily.Push rod 19A can be formed as a rod with a square cross-section. Pistonmember 13 and actuation shaft 14 can be formed unitarily. Joining ring21 and tool plate body 3 a can be formed unitarily. Fastening hole 20 bof arc-shaped locking member 20 for fastening the spring member can beomitted. The number of push rods and their rod insertion holes is notlimited to four, and, for example, can be three or more than four. Theshape and placement and the like of the grease grooves of the push rodsand the arc-shaped locking members can be changed. A lubricating agentother than grease can be coated in advance, or it can be supplied asneeded. Various modifications may be effected therein without departingfrom the scope or spirit of the present invention.

Having described preferred embodiments of the invention with referenceto the accompanying drawings, it is to be understood that the inventionis not limited to those precise embodiments, and that various changesand modifications may be effected therein by one skilled in the artwithout departing from the scope or spirit of the invention as definedin the appended claims.

What is claimed is:
 1. A robot hand tool linkage device for connectingan outer part of a robot hand to a master plate that is connected to anoutput part of a robot hand, comprising: an actuation shaft supported bysaid master plate; means for driving said actuation shaft between alocked position and an unlocked position; a ring-shaped retainer affixedto said master plate surrounding an outer perimeter of said actuationshaft and including a ring-shaped groove; a plurality of radiallydirected rod insertion holes formed in an inner perimeter wall; said rodinsertion holes being directed perpendicular to a motion of saidactuation shaft; a plurality of push rods attached movably in saidplurality of rod insertion holes that transfer the output of saidactuation shaft radially outward; a plurality of arc-shaped lockingmembers free to slide in a radial direction in said ring-shaped grooveunder urging of ends of said push rods; annular joining ring affixed tosaid outer part; an arc-shaped surface on an inner perimeter of saidjoining ring; said arc-shaped surface tapering inward toward saidlocking members; said arc-shaped locking members disengaging saidarc-shaped surface when said locking members are in their unlockpositions; said arc-shaped locking members engaging said arc-shapedsurface when said arc-shaped locking members are urged outward intotheir locking positions; an arc-shaped groove is provided on an outerperimeter part of each of said plurality of arc-shaped locking members;a C-ring shaped spring member is provided in said plurality ofarc-shaped grooves; and said plurality of arc-shaped locking members areelastically urged toward a smaller diameter by said spring member.
 2. Arobot hand tool linkage device as claimed in claim 1, wherein: a taperedjoining surface that joins and locks with an outer perimeter surface ofsaid plurality of arc-shaped locking members is formed on a tool plate.3. A robot hand tool linkage device as claimed in claim 2, wherein: whensaid actuation shaft is at a lock position, said plurality of arc-shapedlocking members abut said tapered joining surface; when said actuationshaft is at a release position, said plurality of arc-shaped lockingmembers have a smaller diameter than said tapered joining surface.
 4. Arobot hand tool linkage device as claimed in claim 2, wherein: anarc-shaped joining surface that can contact said tapered joining surfaceof said tool plate is formed at a location near an outer perimeter ofsaid arc-shaped locking member.
 5. A robot hand tool linkage device asclaimed in claim 1, wherein: a surface contact location that is insurface contact with a portion of a surface of said actuation shaft isformed on a portion of said push rod that contacts an output part ofsaid actuation shaft.